Plug valve assembly



July 6, 1965 P. A. MANOR ETAL 3,192,942

PLUG VALVE ASSEMBLY Original Filed June 3, 1957 5 Sheets-Sheet 1' Fig.5

- mvENToRs PAUL A. Man/ole amass V 50141:?

ATTORNEYS July 6, 1965 P. A. MANOR ETAL 3,

PLUG VALVE ASSEMBLY Original Filed June 3, 1957 5 Sheets-Sheet 21NVENTOR$ PAUZ A. Mm? 0/4215: V 5741151? sz/yayw ATTORNEYS y 6, 1965 P.A; MANOR ETAL 3,192,942

PLUG VALVE ASSEMBLY Original Filed June 3, 1957 5 Sheets-Sheet 3 .Fi 7-7I 76 85 INVENTORS 85 19104 A. M0101? 76 fl 7. 5 v 0/4245: VSMMER BYfwwyw ATTORNEYS y 1965 P. A. MANOR ETAL 3,192,942

PLUG VALVE ASSEMBLY Original Filed June a, 1957 5 Sheets-Sheet 5INVENTORS 1 40.: 4 Man/v2 f1 7 ,/&}4,e4e$ ,jmzzeg United States PatentThis invention relates to plug valves and particularly to stem sealarrangements. This application is a continuation of Serial No. 663,175,filed June 3, 1957 and now abandoned.

The invention particularly concerns special seal constructions which maybe tightened axially on the valve stem without changing the peripheralsealing of the valve stem.

Prior to the invention it was common and accepted practice to sealagainst leakage of line fluid outwardly along the stem of a plug valveby providing a compressible ring of asbestos or like material betweenthe stem and the surrounding bore in the valve cover or casing andcompress the ring axially of the stem by means of a screw threaded orbolted gland. This axial compression resulted in radial expansion of thering into engagement with the bore andthe stem. The force axiallytransmitted through the ring was also effective to urge the innerperipheryof an annular sealing diaphragm assembly against the top of theplug but that force could not be too tight or it would bind the plungagainst normal rotation. Also the radial deformation of the asbestosring relied upon to seal the stem in the opening had to be limitedbecause it might bind the stem against rotation. Thus the propertightening of the gland had to be effected without producing theseexcessive axial and radial forces, and usually a compromise arrangementwas the best possible with the result that these seals were ofteninadequate. This was particularly true after wear in the field and itwas attempted to adjust the seal tight when leakage appeared.Furthermore, even if the gland 'was correctly tightened and the asbestosring properly deformed. at first, the asbestos and other such materialsused in the ring tend to soon set and harden and lose whateverelasticity they may have had and sometimes they even shrink so thatleakage quickly appeared along the valve stem. The worker in the fieldcould only tighten the gland to try to overcome this diiiculty but indoing so he usually produced the undesired excessive radial and axialtransmitted forces at the ring and the packing soon became either sosolid as to act as a brake preventing turning of the valve plug orotherwise deteriorated to the point where further tightening of thegland had no effect on the seal.

It is therefore a major object of the invention'to provide a novel stempacking arrangement for a plug valve wherein axial adjustment of thegland retaining the packing does not change the peripheral sealingcharacteristics of the packing. a

A further object of the invention is to provide a novel seal arrangementfor a plug valve stem wherein concentric deformable rings are interposedbetween rigid axially adjustable members slidably surrounding the valvestem.

A further object of the invention is to provide a novel plug valve stempacking using deformable seal rings made of a tetrafiuoroethylenepolymer, silicone rubber and the like for high temperature service.

FIGURE 1 is a fragmentary view in section showing a lubricated taperedplug valve incorporating an embodiment of the seal of the invention; I

FIGURE 2 is an exploded section showing the seal assembly per so; I

FlGURE 3 is a fragmentary view in section of a fur ther embodiment usingnon-circular cross-section seal rings;

' FIGURE 4 is a fragmentary view partly in section and partly inelevation showing another embodiment of the invention;

FIGURE 5 is sembly;

FIGURE 6 is a fragmentary view partly in section and partly in elevationshowing a further embodiment of the invention; V 7

FIGURE 7 is a fragmentary section showing the relaxed spring washer inthe FIGURE 6 embodiment;

FIGURE 8 is a fragmentary section showing the assembly in the preloadedcondition it occupies during normal operation; 3

FIGURE 9 is a fragmentary section showing the fully deflected springcondition attained upon jacking of the P s; 7

FIGURE 10 is a diagrammatic explanation of the action of the positivestop normally fiat sided spring washer shown in FIGURES 69;

a top plan view of the FIGURE 4 as- FIGURE 10-A is a'diagramfnaticexplanation of the action of a Belleville type spring washer shown inFIGURES 11, 12 and 13; 1

FIGURE 11 is a fragmentary section showing a Bellerille type of springwasher in the FIGURE6' type assem FIGURE 12 is a fragmentary sectionshowing another embodiment of the invention; and

FIGURE 13 is a fragmentary view partly in section and partly inelevation showing another embodiment of the invention;

FIGURE 1 illustrates a generally conventional lubricated plug valveassembly wherein a body 11 is formed with aligned fluid flow passages 12and 13 intersected substantially at right angles by a tapered bore 14 inwhich is rotatably mounted theplug 15 having a through port 1% adaptedto close fluid communication between passages 12 and 13 when disposed asin FIGURE 1, or to be rotated to interconnect passages 12 and 13.Suitable lubricant grooving is indicated at 17 whereby lubricant may beintroduced thereinto and distributed through connectinggrooves to thetapered seating surfaces of the valve plug in the bore. The foregoing isconventional'and not part of the present invention, and any conventionallubricant admission and distribution may be used.

Plug 15 is formed with a rigid stem 18 upstanding from the flat annulartop surface 19. An annular flexible diaphragm 21, which is preferablymade of a flat spring metal ring 22 laminated with a superposed ring 23of asbestos,

rubber or like compressible material has its outer periphery clampedbetween an annular shoulder 24 surrounding the open'top of bore 14 and arelatively heavy body Patented July 6, 1965 3 cover 25 that is rigidlybut removably secured, as by bolts (not shown), to body 11.

Cover 25 has a smooth cylindrical lower bore portion 26 and a threadedupper bore portion 27 spaced from stem 18. A sealing assembly isdisposed within bore 26 around the stem and comprises a fiat rigid metalring 23 that overlies the inner periphery of compressible ring 23, and arigid ring 29 of T-shape in cross-section having a flat bridge 31parallel to and of the same internal and external diameters as ring 28and a leg 32 contacting ring 28.

Disposed in the annular spaces 33 and 34 thus provided are rings 35 and36 of a deformable material such as rubber, nylon or Teflon of circularcross-section, socalled O-rings, which have such diameter as to beradially compressed in the assembly of FIGURE 1 while not confinedaxially because of the sizes of spaces 33 and 34. Teflon and siliconeare less resilient than rubber out are inert with respect to hightemperatures which will destroy ordinary rubber. Silicone rubber may beused in some high temperature applications. When the seal rings 35 and36 are assembled with T-shaped ring 29 and flat ring 28 as shown inFIGURE 1, the assembly comprises a cartridge such as disclosed in thecopending application of Anthony W. Renfro Serial No. 570,812, filedMarch 12, 1956, now United States Letters Patent No. 2,876,987, datedMarch 10, 1959.

Above bridge 31 are disposed in succession a flat ring 37 ofcompressible and expansible resilient material such as synthetic rubberand a flat smooth surfaced metal ring 38. A gland 39 externally threadedinto the cover at 27 may be tightened to urge the entire seal assemblytherebelow against the diaphragm with adequate force to prevent leakageand to provide proper seating force to seat the tapered plug 15 in bore14 and, no matter how tight gland 39 is drawn there is always the sameradial seal provided between the cover and valve stem by the O-ringswhich do not change their condition with tightening of gland 39. Thesmooth circular peripheries of ring 28 and bridge 31 slidably engage thestem and bore 26 as the gland is tightened.

When gland 39 is drawn tight it compresses resilient ring 37 to therebypreload the ring to a condition where its tendency to expand exerts andmaintains the plug seating force, but when the lubricant pressure at theplug seats is increased to jack the plug and body apart ring 37 furthercompresses readily to permit such jacking and to a substantially solidcondition where it offers a positive stop to further separationaldisplacement of the plug with respect to the body to limit the lubricantdischarge space size, and then after the jacking force is no longerapplied ring 37 expands to its preload condition to maintain plugseating force. The size and physical characteristics of ring 37 can beso selected as to accomplish this action. During all of this operationof jacking and return to preload the radial seal assembly moves on thestem without changing the stem seal.

FIGURE 3 shows a variation of the invention wherein radially compressedbut axially free inverted U-shaped flexible deformable seal rings 41 areused in the annular spaces between the leg of the T-ring and the glandand cover.

Where the valve assembly is for mostly high temperature services, thedeformable seal rings are made of a plastic such as silicone rubber, ora tetrafluoroethylene polymer one source of which is sold under the nameTeflon by E. I. duPont de Nemours & Co. Although adequately resilientfor sealing, the tetrafluoroethylene polymer material or silicone rubberis not sufficiently stretchable to go over the flange 31 of FIGURE 2without exceeding its elastic limit and hence for rings made of suchmaterial, so that the two part cartridge structure of FIGURE 2 is used.

FIGURES 4 and illustrate another embodiment wherein a valve plug 42rotatable in tapered bore 43 of body 44 h a rigid operating stem 45 witha cylindrical section 46 surrounded in spaced relation by thecylindrical bore 47 of a cover 48 secured to the body as by bolts 49.The outer periphery of the laminated flexible steel and compressiblematerial diaphragm 51 is clamped between the cover and body.

A rigid fiat-sided metal ring 52 is seated overlying the inner peripheryof the diaphragm with a vertical sliding fit in the space between thebore 47 and stem section 46. A gland 53 has an annular skirt 54extending slidably into the space between bore 47 and stem section 46,and at its lower end is formed with an integral centrally locateddepending leg 55 that extends down to contact ring 52 and definesannular sealing spaces 56 and 57 of about the same size in which aredisposed the radially compressed but axially free rubber, nylon, Teflonor like resiliently deformable material O-rings 58 and 59.

When gland 53 is drawn tight, as by a series of stud assemblies at 61threaded into the cover, the axial force on diaphragm 51 is increased toa desired degree without changing the radial seal of the O-rings in theassembly. If desired an annular groove may be provided in the valve stemat 62 to seat a deformable sealing O-ring 63 of synthetic rubber, nylon,Teflon or the like.

In the embodiment of FIGURE 4 when the plug is jacked from its seat bythe lubricant pressure jacking force component the inherent resiliencyof valve cover 48 is used to controllably limit the jacking movement ofthe plug and hence the separation at the plug and body seating surfacesso that these surfaces will not separate so much that the pressurizedlubricant will merely discharge freely into the line at the point ofhighest pressure and not be spread around the seats. In the embodimentof FIGURES 1-3 the ring 37 limits the jacking movement. In theembodiments of FIGURES 6-12, special spring arrangements are employedfor this particular purpose, as for use in valves wherein the covers maybe too rigid to so function.

Referring to FIGURES 6-11 a rotatable plug valve assembly comprises abody 64 having a rigid bolted-on cover 65 and a usual tapered bore 66 inwhich is seated rotatably a tapered plug 67 having a rigid stem 68 and alubricant reservoir 69 in the stern discharging through a radial passage71 into an annular plug groove 72 opposite an annular seat surfacegroove 73. The usual laminated asbestos-steel diaphragm assembly at 74is clamped between the cover and body at its outer periphery and itsinner periphery seats a rigid flat metal ring 75.

A substantially T-shaped cross-section rigid metal ring 76 has a centralrigid leg 77 contacting ring 75, and deformable O-rings 78 and 79 ofsynthetic rubber, nylon, Teflon, or the like, are disposed in the spacesbetween leg 77 and the stem surface 81 and cover bore 82 respectively.These O-rings are, as in the other embodiments,

radially compressed but freely expansible axially of the stem axis.

A gland 83 is threadedly mounted in the top of bore 72 at 84 and hasradial clearance with stem surface 81. The upper flat annular surface 85of ring 76 and the lower ilat annular surface 86 of gland 83 are bothinwardly inclined and parallel, and FIGURE 6 shows an annular springwasher 87 therebetween in its deformed preloaded normally operativeposition. The desired degree of preload on spring 87 may be adjusted bymeans of the threaded gland 83.

As shown in FIGURE 7 spring ring 87 relaxed with respect to the assemblyis a flat-sided circular annulus which is essentially a flat resilientsteel washer. For example it may be of AS 101 or SAE 1074 steel heattreated to have a surface hardness of about 35-45 Rockwell C- Scale.When gland 83 is tightened the Washer 87 is axially trapped betweensurfaces 85 and 86, with ring line contact at opposite edges asindicated at 88 and 89, and the washer is thereby torsionally stressedor twisted toward the condition shown in FIGURES 6 and 8. The

degree of twist is not known, but for clarity, it is shown inexaggerated form. In twisted condition, with gland 83 serving as anabutment, stressed spring 87 provides a resilient seating force on theplug, and as shown in FIG- URE it has been found that the deflection ofsuch an annular plate spring increases with load practicallyproportionately up to a certain point indicated at L in FIG- URE l0 andthen any increase in load beyond that point will result in 'a muchsmaller proportional deflection increase until at another pointindicated at L; it acts essentially as a positive stop to further plugdisplacement.

This is taken advantage of in the invention by so deflecting the spring87 by gland adjustment in assembly that it is adequately preloaded tothe point indicated as L in FIGURE 10 to exert a plug seating force thatresists any tendency of the plug to unseat due to components of linefluid pressure, but when stronger lubricant pressure is applied, thespring 87 will afford relative strong resistance as indicated in FIGURE10 on the curve between 7 L and L and in the assembly will by the time Lis reached have assumed the condition shown in FIGURE 9 where it isconfined between surfaces 85 and 86. This FIGURE 9 position represents apositive stop to separation of the plug valve and body seats, and it canbe designed to provide a predetermined film thickness of lubricant atthose surfaces. When the lubricant jacking pressure is released, thespring 87 reasserts itself to expand and exert the preload seatingpressure onthe plug 67.

FIGURE 11 illustrates an embodiment wherein the annular spring 91, whichserves as the plug seating spring is of frusto-conical configurationwhen relaxed, being a normally dished annular plate spring of the kindknown as a Belleville spring having its inner peripheral edge 92 incontact with smooth flat surface 93 of T-shaped ring 94 and its outerperipheral edge 95 in contact with smooth flat surface 96 of gland 97.Surfaces 93 and 96 r are parallel and perpendicular to the stem axis.Spring 91, when gland 97 is axially tightened, assumes a preloaded plugseating position, and collapses further under lubricant pressure to apositive stop relation between surfaces 93 and 96 to provide exactly thecorrect seat separation for uniform introduction of plastic lubricantaround the plug seating surfaces.

The curve of FIGURE 10A illustrates the load-deflection characteristicsof a Belleville spring at various deflections. As shown, the curve ofload vs. deflection rises rapidly at small deflections from its normalrelaxed ish state, but at point C levels out and becomes substantiallyflat and remains so to the full deflection position. This type of springhas peculiar utility where the valve has no adjustable gland. The partsare so related that installation of the gland 131 compresses andpreloads the spring 91 through C approximately to the horizontal flatregion of the curve, which is thenormal plug seating pressure, and whenjacking pressure is applied the spring 91 quickly collapses to thepositive stop condition, which condition determines the maximumthickness of the lubricant film. I 7

Referring to FIGURE 12, a plug valve body casing 98 has a tapered bore99 in which is rotatably. seated a tapered plug 101 having a rigid stem162 extending through a cover 103 bolted onto body 98. The plug and boresurfaces have opposed annular lubricant distribution grooves 164 and1115 supplied as in FIGURE 6, and the usual laminated steel and asbestosdiaphragm 106 has its outer periphery clamped between the cover andbody.

A rigid flat annular metal ring 107 overlies the inner periphery of thediaphragm, and a gland 1138 is slidably disposed in the space betweenthe valve stem and cover bore 169 with an integral central annulardepending leg or rib 111 contacting ring 107. Teflon or like resilient-O-rings 112 and 113 are wally free and radially compressed in the spacesbetween rib 111 and the stem and bore respectively.

Above rib 111, the valve stem is formed with an annular groove 114 inwhich is radially compressed a similar deformable O-ring 115 to sealwith gland 108.

A fiatrannular rigid retainer plate 116 freely surrounds theupper end ofstem 102 and it is connected to cover 1% by a series of equidistantlyspaced stud assemblies (only one shown) 117. Between the bottom of plate116 and the top of gland 108 is provided an annular dished platespring113 of the Bellev-ille type-which is com pressed when studs 117are tightened to axially shift gland 1 .98 and increase the sealingpressure on the-diaphragm. As in the FIGURE 11 embodiment, spring 118 vis compressed or preloaded to exert a plug seating pressure, and to apoint where application of lubricant jacking PIfiSSlll'Q'CQllfiPSES itto a substantially fiat position wherein it strongly resists furtherdeformation and acts as a positive stop to limit the valve seatseparation to a predetermined small value. The top plate 116 is providedwith an annular sheet metal plate 119 held thereon by studs 117 thatpass through it and with its inner periphery clamping a flexible packingannulus 120 of asbestos or the like tight with stem 102 to provide adust and weather tight joint.

FIGURE 13 illustrates another embodiment wherein a valve plug 12rotatable in tapered bore 112 of body 123 has a rigid operating stem 124with a cylindrical section 125 surrounded in spaced relation bycylindrical bore 128 of a cover 127 secured to the body as by bolts 128.The outer periphery of the laminated flexible steel and compressiblematerial diaphragm 129 is clamped between the cover and body. 5

A rigid flat-sided metal ring 130 is seated overlying the innerperiphery of the diaphragm with'a vertical sliding fit in the spacebetween the bore 126 and stem section 125. A gland 131 has an annularskirt 132 extending slidably intolthe space between bore 126 and stemsection 125, and at its lower end, face 133 is formed flat and parallelwith the flat side of ring 130.

Disposed between end face 133 and the ring 130 is a Belleville spring134 having an inner peripheral edge 135 in contact with the top flatsurface 136 of a T-shaped cross-sectiqn'ring 137 and its outerperipheral edge 138 in contact with end face 133 of gland 131. The flatend face 133 is parallel to flat surface 136 and both are per pendicularto the stem axis.

The T-shaped ring 137 has a central rigid leg 139 contacting a flat sideofring 130, and deformable Oarings 140 and 141 of synthetic rubber,nylon, Teflon or the like are disposed in the spaces between leg 139 andthe V surface of stem cylindrical section 125 and cover bore 126respectively; These O-rings are, as in the other embodiments, radiallycompressed, but freely expansible axially.

When the gland 131 is drawn tight, as by a series of springs load curve.

without departing from the spirit or essential characteristics thereof.The present embodiments are therefore to be considered in all respect asillustrative and not restric ti ve, the scope'of the invention beingindicated by the appended claims rather than by the foregoingdescription,

and all changes which come within the meaning and range of equivalencyof the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States LettersPatent is:

1. In a plug valve, a body having a plug seating bore, a plug rotatablymounted in said bore and having a stem projecting through a bodyopening, a stem packing comprising two axially spaced rigid annularmembers positively separated by an intermediate annular leg rigid withone of them and extending into abutment with the other, annulardeformable substantially non-elastic O-rings radially compressed betweenopposite sides of said leg and the stem and body opening respectively,and an axially adjustable gland on said body surrounding said stemoutwardly of the packing and adapted when adjusted in one direction todisplace said members as a unit toward the top of said plug topositively transmit plug seating pressure from said gland to said plugwithout atleoting the radial seal of said packing in the assembly.

2. In the plug valve defined in claim 1, the axially outermost of saidmembers being integral with said gland and said leg being integraltherewith.

3. In a plug valve, a body having a plug seating bore, a cover over thelarge end of said bore having an opening therethrough, a valve stemprojecting from the plug through said opening, an annular diaphragmsurrounding the plug-connected end of said stem and having its outerperiphery clamped between the cover and body, a first rigid ringsurrounding the stem and overlying the inner periphery of saiddiaphragm, a second rigid ring surrounding said stem with one of saidrings having a rigid leg engaging the other ring so as to defineconcentric seal ring spaces with the stem and cover openingrespectively, deformable radially compressed substantially non-elasticseal rings in said spaces, and means for positively axially displacingsaid rigid and deform-able rings as a unit to exert plug seatingpressure against and through the inner periphery of said diaphragm.

4. In a plug valve assembly, a body having a through passage for fluidflow and a tapered bore intersecting said passage at right angles, aported plug rotatably mounted in said bore adapted to be turned betweenpositions where it blocks said passage or permits fluid flow through thevalve assembly, means for introducing a plastic sealant film between theseating surfaces of the plug and body bore, a stem for the plugprojecting through an opening in the body, an axially rigid sealassembly surrounding said stem within the body opening axially outwardof said plug, said seal assembly comprising inner and outer resilientO-rings in radially compressed engagement with adjacent surfaces of thestem and opening respectively, .an axially adjustable gland surroundingsaid stem and mounted on said body axially outwardly of said sealassembly, said gland being adjustable toward the plug so that said sealassembly positively transmits plug seating pressure without affectingthe radial seal of said seal assembly in the opening, separate resilientmeans surrounding said stern interposed between said gland and said sealassembly adapted to be compressed and transmit plug seating force whensaid gland is adjusted to attain plug seating pressure position and whenso compressed serving to urge the plug into seating engagement with saidtapered bore and means for increasing the sealant pressure at saidsurfaces to separate said plug and body against the force of saidcompressed resilient means. i

5. In a plug valve assembly, a body having a through passage for fluidflow and a tapered bore intersecting said passage at right angles, aported plug rotatably mounted in said bore adapted to be turned betweenpositions where it blocks said passage or permits fluid flow through thevalve assembly, means for introducing a plastic sealant film between theseating surfaces of the plug and body bore, a stem for the plugprojecting through an opening in the body, an axially rigid sealassembly surrounding said stem within the body opening axially outwardof said plug, said seal assembly comprising inner and outer resilientO-rings in radially compressed engagement with adjacent surfaces of thestem and opening respectively, an axially adjustable gland surroundingsaid stem and mounted on said body axially outward of said sealassembly, and separate compressible and expansible resilient meanssurrounding said stem interposed between said gland and said sealassembly to urge the plug into seating engagement with said taperedbore, said resilient means being compressed by adjustment of said glandto a condition where it tends to expand and react against said gland toexert a desired plug seating force, and said resilient means having suchcharacteristics that when adjusted to such condition further load over apredetermined range due to gland adjustment does not materially alterits compression or said plug seating force, thereby permittingadjustment of said gland to limit separation of said surfaces whenjacking pressure is applied to said sealant without appreciably changingsaid plug seating force, said resilient means comprising spring meanshaving substantially constant load vs. deflection characteristics withina predetermined range of compression and being prestressed within saidrange in the assembly.

6. In a plug valve assembly, a body having a through passage for fluidflow and a bore intersecting said passage at right angles, a ported plugrotatably mounted in said bore adapted to be turned between positionswhere it blocks said passage or permits fiuid flow through the valveassembly, a rotatable stern for the plug projecting through an openingin the valve body, and means at said opening for exerting a desired plugseating pressure in the bore and for sealing said opening around thevalve stem comprising a gland surrounding said stem and axiallyadjustable with respect to said stem and sealing means within theopening surrounding the stem comprising an annular rib rigid and movablewith the gland and projecting axially toward said plug in radiallyspaced relation to the adjacent surfaces of the stem .and thesurrounding opening and an axially rigid ring section that is axiallyrigid with aid rib, said gland, rib and ring section defining opposedannular recesses with said opening, said recesses opening only radiallyof the stem to said adjacent surfaces on said stem and openingrespectively, and radially compressed O-rings of deformable sealingmaterial within said recesses.

7. In a plug valve assembly having a body provided with a throughpass-age and a tapered bore perpendicular to said passage, a taperedported plug rotatably mounted in the bore to block or allow flow offluid through the passage, an operating stem for the plug extendingthrough an opening in the body, seal means surrounding the stem Withinthe opening comprising axially rigid means defining opposed annularrecesses opening radially of the stem to related surfaces of the stemand body opening respectively, radially compressed deformable seal ringsin said recesses, and means for adjusting said seal means as a unittoward and effectively against the upper end of said plug formaintaining said plug seated in said bore with a predetermined pressure,the plug seating force being transmitted positively through said axiallyrigid means, and resilient means compressed by adjustment of said sealadjusting means cooperating with said seal means in urging the plug intoseating engagement with said tapered bore.

8. In a plug valve assembly having a body provided with a throughpassage and a tapered plug seating bore perpendicular to said passage, atapered ported plug rotatably mounted in the bore to block or allow flowof fluid through said passage, an operating stem for the plug having acylindrical portion extending through a surrounding cylindrical portionof an opening in the body, seal means surrounding said stem at saidcylindrical portion within the open-ing disposed in effective forcetransmitting abutment with the upper end of the plug and comprising twoseparate members in axially rigid contact defining opposed annularrecess opening radially to the stem to related cylindrical surfaces ofthe stem' and opening respectively, one of said members beingsubstantially T-shaped and consisting of an annulus with an integral legprojecting from one side axially of said stem in spaced relation to boththe stem and said opening, and the other member being an annulus intight abutment with the free; end of said leg, radially compresseddeformable O-rings in said recesses, and means for adjusting said sealmeans as an axially rigid uni-t axially of said stem for determining andmaintaining the seating pressure of said plug in said bore comprising agland adjustably mounted in said body and metallic annular spring washermeans compressed between said gland and the adjacent seal member, theplug seating force being transmitted positively through the compressedspring washer means and through said seal unit without altering thecharacter of the radial seal at the surfaces of said opening and stem.

'9. In the plug valve assembly defined in claim 8, said adjusting meanscomprising a gland axially adjustably mounted within said opening.

10. In the plug valve assembly defined in claim 9,'

said gland and said adjacent seal member having axially opposed parallelannular :surfiaces within said opening lying in planes inclined withrespect to the axis of said stem, and said spring washer means beingdisposed between said surfaces.

11. In a plug valve assembly having a body provided with a throughpassage and a tapered bore perpendicular to said passage, a taperedported plug rotatably mount-ed in the bore to block or allow flow offluid through the passage, a rotatable operating stem for the plugextending through an opening in the body, seal means surrounding thestem within the opening consisting essentially of axially rigid meansdefining opposed annular recesses opening radially of the stem torelated surfaces of the stem and body opening respectively and radiallycompressed resilient seal rings in said recesses, means for adjustingsaid seal means axially of said stem for maintaining the plug seated insaid bore with a predetermined pressure, the plug seating force beingtransmitted positively through said axially rigid means, md resilientmeans comprising a metallic spring washer.compressed in the assemblyinto actively resilient condition by adjustment of said seal adjustingmeans cooperating with said seal means in urging the plug into seatingengagement with said tapered bore.

1-2. In a plug valve assembly having a body provided with a throughpassage and a tapered bore perpendicular to said passage, a taperedported plug rotatably mounted for seating in the bore to block or allowflow of fluid through the passage, an operating stem for the plugextending through an opening in the body, seal means surrounding thestem within the opening comprising an annular structure which is rigidunder axial compression and defines opposed annular recesses openingradially of the stem to related surfaces of the stem .and body openingrespectively, radially compressed deformable seal rings located in saidrecesses, annular metallic spring washer means within said openingsurrounding said stem adjacent said seal means, and a gland memberassociated with said opening and adjustable axially to axially com presssaid annular metallic spring washer means and urge said seal means as aunit operatively against the upper end of said plug to provide andmaintain a desired seating force on said plug that is transmittedthrough the annular structure of said seal means and said compressedresilient means.

13. In a plug valve assembly, a body having a through passage for fluidflow and a bore intersecting said passage at right angles, a ported plugrotatably mounted in said bore adapted to be turned between positionsWhere it blocks said passage or permits fluid flow through the is f avalve assembly, a rotatable stem for the plug project-ing through anopening in the valve body, and means at said opening for exerting .adesired plug seating pressure in the bore and for sealing around thevalve stem comprising an annular gland surrounding said stem and axiallyadjustable with respect to said stem and sealing means within theopening surrounding the stem comprising an annular rib rigid withthe-gland and projecting axially toward said plug in radially spacedrelation to the adjacent surfiace of the stern, said gland, rib and stemdefining .an annular recess opening radially to the stem, a radiallycompressed O-ring of deformable sealing material within said recess,and-means extending rigidly between said rib and the upper end of saidplug for rigidly transmitting gland adjustment to said plug.

'14. In a plug valve assembly having a body provided with a throughpassage and a tapered bore perpendicular to said passage, a taperedported plug rotatably mounted for seating in the bore to block or allowflow of fluid through the passage, an operating stem for the plugextending through an'opening in the body, seal means surrounding thestem within the opening comprising an annular structure which is rigidunder axial compression and defines opposed annular recesses openingradially of the stem to related surfaces of the stem and body openingrespectively, radially compressed deformable seal rings located in saidrecesses, an annular metallic spring washer within said openingsurrounding said stem adjacent said seal means, and a member associatedwith said opening in operative motion transmitting engagement with saidseal means and adjustable axially to compress said spring washer andurge said seal means as a unit operatively against the upper end of saidplug to provide and maintain a desired seating force on said plug thatis transmit-ted through the annular structure of said seal means andsaid compressed spring washer means, said member being a glandadjust-able axially of said body opening, and said spring washer meansbeing interposed between the gland and the rigid annular structure ofsaid seal means. i V

:15. In the plug Valve assembly defined in claim 14, said adjustablemember and said annular seal structure having axially spaced surfacesfacing each other longitudinally of said stem, and said resilient meansbeing an annular plate spring of generally dished shape clear of contactwith said valve stem and having its outer periphery engaged with one ofsaid surfaces and its. inner periphery engaged with the other of saidsurfaces.

'1-6. In a plug valve assembly having a body provided with a throughpassage and a tapered bore perpendicular to said passage, a taperedported plug rotatably mounted in the bore to block or allow flow offluid through the passage, a rotatable operating stem for the plugextending through an opening in the body, seal means surrounding thestem within the opening consisting essentially of' axially rigid meansdefining opposed annular recesses opening radially of the stem torelated surfaces or" the stern and body opening respectively .andradially compressed resilient O-rings in said recesses, means foradjusting said seal means axially of said stem and operatively vagainstthe upper end of said plug for maintaining the plug seated in said bore,the plug seating force being transmitted positively through said axiallyrigid means, and spring means disposed between said seal adjusting meansand said axially rigid means compressed in the assembly by adjustment ofsaid seal adjusting means into actively resilient condition for urgingthe plug into seating engagement with said tapered bore with asubstantially constant pressure, said spring means'in the assemblypermitting separational displacement of the plug and bore seatingsurfaces'within a predetermined range without appreciable change in saidseating pressure.

17. In the plug valve assembly defined in claim 16,

means limiting compression of said spring means to provide a positivestop defining the maximumseparation of said plug and bore seatingsurfaces.

References Cited by the Examiner UNITED STATES PATENTS Nordstron137246.19 Atkinson et a1. 137-24615 X Allen et :11. 285111 Migny 2671Griefen 27795 Kohler 2671 X 2,876,987 '3/59 Renfro 251-214 3,03 0,067 4/62 Manor 251-214 FOREIGN PATENTS 958,598 9/49 France. 1, 1 3 0,592 10/56France.

5/52 Germany. 6/52 Germany.

1. IN A PLUG VALVE, A BODY HAVING A PLUG SEATING BORE, A PLUG ROTATABLY MOUNTED IN SAID BORE AND HAVING A STEM PROJECTING THROUGH A BODY OPENING, A STEM PACKING COMPRISING TWO AXIALLY SPACED RIGID ANNULAR MEMBERS POSITIVELY SEPARATED BY AN INTERMEDIATE ANNULAR LEG RIGID WITH ONE OF THEM AND EXTENDING INTO ABUTMENT WITH THE OTHER, ANNULAR DEFORMABLE SUBSTANTIALLY ONE-ELASTIC O-RINGS RADIALLY COMPRESSED BETWEEN OPPOSITE SIDES OF SAID LEG AND 